There aren't many cases out for the iPhone yet (that are in-stock/shipping before Mid-July), but at a local Best Buy I picked up this dark "smoke" colored gel/plastic case. It's smooth (so it doesn't stick to your pocket like silicone would), and fairly cheap at $16. I'm going on a vacation for most of July, and when I get back, I'm probably going to order a Power Support "Anti-Glare" Film and possibly a different, hard plastic case as well.

They also had the Griffin Reveal at Best Buy, but for $25, the build quality isn't that good, and the clear plastic back is a fingerprint/scratch magnet.